Tag Archives: 4L

Results: 2 of the 4 samples (2L & 3L) look perfect (<20% of cDNA in the 25-150bp range). 6L has <20% of the cDNA in the 25-150bp range (which is perfect), but exhibits a “smear” from ~250-500bp. cDNA in this range suggests overamplification, which will skew gene expression profile. Can repeat PCR for 6L using outer gel slices and reduce the number of cycles to prevent overamplification, if desired. Spoke to Steven and since these samples won’t be used to evaluate gene expression (they’re for SNP discovery), we won’t worry about it for the time being.

Sample 4L has some very strange signals being generated in the ~500-800bp range. Additionally, the virtual gel image (not shown) shows a great deal of smearing, unlike the other samples.

Emulsion PCR was performed with the two inner gel bands cut out earlier today according to the Ambio WTK protocol. PCR was run for 15 cycles. After the PCR, the samples were cleaned up using the Invitrogen PureLink PCR Micro Kit, according to the Ambion WTK protocol. The cleaned up cDNA (referred to as “libraries” from now on) was spec’d prior to running on the Bioanalyzer.

Results:

All samples look good EXCEPT for 4L. It has a terrible 260/230 ratio and has a very low concentration, relative to the other three samples. Although not pictured here, the absorbance curve of the 4L sample was extremely poor and broad, unlike the other three samples.

Ligation reactions from yesterday were subject to reverse transcription according to protocol. Master mix workup info is here. Samples were incubated @ 42C, 30mins and then cleaned up using the Qiagen MiniElute PCR Purification Kit, according to the Ambion WTK protocol.

After RT rxn, samples were run on a Novex 6% TBE-Urea gel according to Ambion WTK protocol. Samples were loaded, left to right: 2L, 3L, 4L, 6L. Ladders are to the left of each sample. The break in the smear in the 6L sample is a tear in the gel.

The recommended range of cDNA (100-200bp) were excised from the gel and were cut into four pieces, according to the Ambion WTK protocol. The two outer gel slices from each sample will be stored @-20C. Then proceeded to the emulsion PCR. Here is an image of the gel after the cDNA was cut out:

RNA from yesterday was speedvac’d to dryness and resuspended in 3uL of nuclease-free H2O. Samples were mixed with Adaptor Mix A and hybridized according to Ambion WTK protocol. Samples were then ligated for 16hrs @ 16C, according to Ambion WTK protocol.

Samples from 20091203. 0.5uL was removed from each and transferred to separate tubes and diluted to < 5ng/uL for subsequent Bioanalyzer analysis using the Pico chip. Samples were fragmented using RNase III according to the Ambion WTK protocol and then cleaned up/concentrated using the Invitrogen RiboMinus Concentration Module according to the Ambion WTK protocol.

Samples were spec’d prior to running on the Bioanalyzer:

Concentrations/absorbance values are not accurate when using the NanaDrop after using the RiboMinus Concentration module, according to the Ambion WTK protocol. However, yields seem pretty good…

Total, mRNA and fragmented mRNA from each of the four samples was run on the Pico chip with the Eukaryote Total RNA Bioanalyzer protocol.

Results:

The 2L tot (total RNA) and 3L tot (total RNA) samples are clearly very good quality. 2L tot does exhibit some very slight degradation, though. 4L tot (total RNA) and 6L tot (total RNA) show a much greater degree of degradation. All mRNA samples show complete removal of any trace, contaminating rRNA. The fragmented samples (the last four samples on the gel image above) all appear to be perfect. The 4L frag sample simply has less RNA loaded and that is why it is not as dark as the other three fragmented samples. Despite the degradation in the 4L tot and 6L tot samples, the fragmentation profile looks good and we will proceed with making the cDNA libraries for those samples.

RNA Precipitation

Samples were pelleted for 30mins, 16,000g @ 4C. Supe was discarded, samples quick spun, residual supe removed and then washed with 1mL 70% EtOH. Tubes were vortexed until pellet came off of bottom of tube and then spun 15mins, 16,000g @ 4C. Supe was discarded, samples quick spun, residual supe removed and then resuspended in 250uL of 0.1% DEPC-H2O in preparation for mRNA isolation using the Ambion Micro PolyA Purist Kit.

mRNA Isolation

Clean RNA from earlier today was processed according to the Ambion Micro PolyA Purist Kit to isolate mRNA. This procedure was done two times to ensure full mRNA enrichment of the samples. Samples were then spec’d.

Results:

Yields:

3L – 10.66 ng/uL x 200uL = 2.132ug

6L – 6.97 ng/uL x 200uL = 1.394ug

2L – 10.89 ng/uL x 200uL = 2.178ug

4L – 6.43 ng/uL x 200uL = 1.286ug

mRNA Precipitation

Precipitation of mRNA from earlier today in preparation for fragmentation. Fragmentation requires mRNA volumes of <8uL, so after precipitation I will resuspend pellets in 8uL of 0.1% DEPC-H2O. Will use 1ug (this means 1/2 of 3L and 2L & all of 6L and 4L) of mRNA from each sample for precipitation. Remainder of 3L and 2L samples were stored @ -80C in “Herring RNA Box #1.”Samples were precipitated by adding 0.1 volumes 5M ammonium acetate, 1uL glycogen and 2 volumes of 100% EtOH. Samples were incubated O/N @ -20C.